This invention is concerned mainly with printing apparatus, and specifically with such apparatus which rely upon non-impact imaging processes and somewhat simulate in appearance and function devices known as typewriters.
Intensive efforts in research and development in recent years have resulted in many improvements in printing devices. Many modern typewriters exhibit sophisticated characteristics which enable them to produce superior copy in both manual and automatic modes. For instance, instead of the usual type of key-moving carriage arrangement used in most typewriters, at least one typewriter utilizes a rotatable "daisy wheel" which moves in a direction transverse to the paper to be printed upon, thereby eliminating carriage movement. Likewise, developments have been made which have resulted in quieter typewriters, as well as typewriters which are less complex mechanically which results in greater reliability.
The greater printing speeds now obtainable have permitted very efficient automatic modes to be realized. Peripheral equipment such as magnetic card and tape units are commonplace. These memory and command units provide ease of error correction, data storage and low quantity line copy reproduction. Some presently known typewriters even have the capability of receiving and processing commands from computers.
Even with the advent of electronic components such as the keyboard disclosed in U.S. Pat. No. 3,778,817, most modern typewriters are relatively noisy since some impact mechanism must usually strike the paper or other receiving medium employed. Likewise, while the reliability of typewriters has been greatly increased, a relatively large number of parts are still employed. Additionally, the mechanical impact printing means generally employed limit either the maximum printing speed or the cost due to the need for multiple parallel printing elements to achieve high printing speeds.